The problem posed is as follows: in a certain number of applications, for example management of the rotation of a motor vehicle steering column, it is necessary to be able to code the position of the steering wheel absolutely over a plurality of rotations (approximately 5). Now, when angle sensors are used which only provide absolute coding of the angular position over one rotation, it remains to code the rotation in progress. This cannot involve a simple incremental rotation counter, as the precise position of the steering wheel must be precisely identified even at starting. Consequently, it is absolutely necessary to code the rotation in addition to the coding over 360°.
Solutions employed up to now use, for example, magnetic technologies associated with mechanical gearing solutions. The configurations employed are generally eccentric relative to the steering column, and must be so designed as to occupy little space, as the available under-wheel volume is small. It is therefore necessary to employ reducing gear trains and therefore to use mechanical systems requiring a certain precision, more expensive to manufacture and even assemble.